Abstract: 【Objective】 Apple skin wrinkling, caused by water loss during storage, is a critical factor that impacts the quality and taste of the fruit. The cuticle and wax layer of apple fruit play an important role in inhibiting water transpiration and respiration. Therefore, the qualitative and quantitative determination of wax and cuticle fractions in apples during storage can help enhance future fruit storage practices. Although studies have been conducted on the effects of various rootstocks on apple fruit quality, antioxidant activity, and disease resistance, the impact of different rootstocks on fruit wax and cuticle during apple storage has not been reported. SH6 and M26 are two dwarf interstocks commonly utilized in the cultivation of "Fuji" apples in northwest China. The former was selected by Shanxi Fruit Tree Institute, and the latter was chosen by Dongmaolin Experimental Station in Britain. In this study, 'Fuji' apples with SH6 and M26 intermediate rootstocks were used as test materials. Comparison of differences in weight loss, respiration intensity, and epidermal wax morphology and structure during storage of 'Fuji' apples with SH6 and M26 as intermediate rootstocks.【Methods】 In this study, the weight loss of two types of rootstocks during storage was measured using the gravimetric method. The changes in respiration rate of two rootstocks during ambient storage were measured using a fruit and vegetable measuring instrument. Morphology of the epidermal wax layer observed through scanning electron microscopy. The waxy layer and cuticle of the fruit epidermis were extracted using organic solvents such as chloroform and methanol. The total amount of cutin and wax, as well as the content of various monomer components, were analyzed using GC-MS. In order to compare the storage characteristics of fruits and the differences in horny and wax morphology and composition between the two rootstocks.【Result】 The results showed that the weight loss and respiration rate of SH6 fruits were significantly lower than those of M26 fruits. There were significant differences in surface wax morphology and thickness between SH6 and M26. The wax on the surface of SH6 fruit is relatively smooth with a few wide gaps and depressions. The surface of M26 fruit is densely covered with waxy roughness and depressions. With the prolongation of storage time, the wax on the surface of SH6 fruit became coarser, and the gaps and depressions increased while the gap spacing decreased. However, the waxy depression on the fruit epidermis of M26 is more pronounced, with larger and wider gaps visible. The thickness of the epidermal wax layer, total wax, and total cuticle were also significantly higher than those of M26 fruits during ambient storage. The content of 28 common cuticle components in SH6 fruits was significantly higher than that in M26 fruits. This includes 14 fatty acids, 7 hydroxy fatty acids, 2 dicarboxylic acids, and 5 alcohols. The content of 34 wax components in SH6 fruits was significantly higher than that in M26 fruits. These components include 5 alkanes, 6 alcohols, 4 fatty acids, 12 esters, 2 aldehydes, and 4 other substances. In addition, SH6 fruits contained four unique components: arachidonic acid, 18-hydroxy-9,12-octadetadienoic acid, ursolic acid methyl ester, and butyl eicosanate. M26 fruits contained three unique components: octadecanoic acid, 7,10,13-eicosatrienoic acid, and behenic acid ethyl ester. Correlation analysis revealed a significant negative correlation between the weight loss rate of fruit during storage and the thickness of the wax layer. This suggests that fruit with thicker wax layers and cuticles experience lower rates of weight loss. The weight loss rate was positively correlated with hydroxyl fatty acids and esters, indicating that substances with higher hydrophilicity facilitated water evaporation more effectively. Respiratory intensity was negatively correlated with the thickness of epidermal wax and cuticle wax. This suggests that the thicker the wax layer and cuticle, the lower the respiratory intensity of fruits. Respiratory intensity was positively correlated with the levels of hydroxyl fatty acids and dicarboxylic acids, suggesting that these compounds were advantageous for gas exchange both within and outside the fruit epidermis.【Conclusion】 Compared with M26 fruit, SH6 fruit had lower weight loss and respiration rate during ambient storage, and the surface morphology of the epidermis wax layer was smoother. SH6 fruit had a thicker epidermal wax layer and a richer cuticle and wax content, resulting in lower weight loss and respiration rate during storage.
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